The invention relates to solar water heaters and more particularly to the type in which sunlight impinges on an insulated blackened surface in thermal contact with water passages.
Many heaters of this type have been developed and the possibility of more widespread use of these and related devices is under increasing scrutiny. Aside from the flexible plastic bag type construction, which is not relevant to the instant invention, there are many prior art heaters whose operation is similar in principle and structure to that disclosed herein. These structures utilize a light-transmitting pane of plastic or glass to admit light to a blackened surface which is in contact with flowing water which is channelized by means of maze-type baffles, tubes, or corridors stamped in the blackened surface itself.
These heaters are not necessarily inefficient or inferior, but uniformly suffer one drawback from a practical standpoint which is the expense required to produce the units, especially on a small scale. Heavy presses or dies are required in their manufacture so that mass production is necessary for economical production. Another type utilizes metal tubing welded or soldered to the light absorbing sheet so that either considerable labor or expensive jigs would be required in manufacture.